Summary

A small group of paleontologists has been asserting that evolution sometimes takes a holiday, pointing to examples of entire communities of marine animals that remain unchanged for millions of years. Claims of such "coordinated stasis" have galvanized the paleobiology community as researchers try to test the idea by studying how animal communities fared over tens of millions of years. The first results to come in are "a mixed bag," researchers concede. Yet confirmation of even occasional episodes of coordinated stasis in the fossil record could have major ramifications for understanding evolution.